Breast cancer and bone mineral density: The Marburg Breast Cancer and Osteoporosis Trial (MABOT II)

Objectives The current case-control study is the first to examine the relationship between bone mineral density (BMD) measured by dual-energy X-ray absorptiometry (DXA) and quantitative ultrasonometry (QUS) in pre- as well as postmenopausal women with breast cancer compared to healthy matched controls. Methods Among 1422 women (premenopausal, n = 238, postmenopausal, n = 1184), BMD and QUS were measured. In total, 541 of the women had an incident diagnosis of breast cancer (122 premenopausal, 419 postmenopausal) without prior breast cancer treatment. Because of significant intergroup differences in multiple risk factors, a matched-pair analysis (88 premenopausal and 402 postmenopausal women with and without breast cancer) was performed. Additionally, a multiple linear regression analysis was undertaken, odds ratios were determined and subjects grouped according to quartiles of DXA and QUS results. Results DXA results (except the L1-L4 Z-score) were significantly higher in postmenopausal women with breast cancer even after a matched-pair analysis was performed (p < 0.05). In premenopausal women, we observed no significant differences in DXA results between the groups. QUS results in pre- and postmenopausal women with breast cancer were significantly higher compared with their matched controls (p < 0.001 for all, except for speed of sound in premenopausal patients, p < 0.05). Odds ratios for breast cancer risk in the second, third and fourth quartiles compared with the lowest quartile were significantly different for a number of variables. Conclusions Our results showed significantly higher BMD irrespective of the method and site of measurement in postmenopausal women with breast cancer compared to controls, even after matching for possible confounders for the first time.